Rossby wave hydraulics

Models are considered for rotating flows over sills, through straits, and a long coasts where the variation in geometry in the how direction is slow bu t otherwise unrestricted. In addition to the (rotation-modified) free surfa ce waves of nonrotating open channel hydraulics, with their predominantly v ertical signature, slow Rossby or vorticity waves are possible when the bac kground potential vorticity varies. In all but the simplest cases the conse rvation of energy and momentum fluxes is no longer sufficient to determine the flow behavior. Various additional modeling assumptions are reviewed, an d time-dependent finite-amplitude and weakly nonlinear theories that includ e long Rossby wave dynamics are summarized.